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Republican strategist: GOP is polling within margin of error in 10 of 12 key races

Outside groups have spend $190 million in Senate races as of October 23

Even before a second Republican Senate candidate tripped over incendiary comments about rape, GOP leaders in Washington knew that their once promising chances of winning control of the Senate had diminished.

Whether Richard Mourdock of Indiana can move past his controversial remarks and stabilize his campaign remains to be seen. Either way, once confident Republicans across the country now face the nail-biting final days of campaigning and a highly uncertain outcome on Election Day.

That's a big change from two years ago when Republicans made major gains in the midterm election and had reason to believe they could take back the Senate this year. But, in fact, Democrats now appear well-positioned to retain their slim majority and with it the ability to influence much of the Washington agenda during the next two years whether President Barack Obama is re-elected or former Massachusetts Gov. Mitt Romney succeeds him.

Political operatives in each party caution that there are more toss-up races this year than in recent memory, so it's very hard to predict the outcome which they agree could be influenced heavily by the presidential ballot.

"We are cautiously optimistic that we'll keep the majority this year," said Matt Canter of the Democratic Senatorial Campaign Committee, which coordinates Democratic campaigns. He pointed to Democratic Senate candidates who are doing unexpectedly well in several red states, which is forcing Republicans to focus their energies and resources where they didn't expect to have to.

"Republicans are spending millions of dollars playing defense in five of the 10 Republican-held seats on the map," Canter said. "Pundits didn't predict that."

Republicans, who acknowledge they faced a number of setbacks, have been buoyed recently by the resurgence of Mitt Romney's presidential bid and are hopeful his momentum will carry over to Senate races. Romney recently cut ads for two GOP Senate candidates, which will test that theory.

"What the first (presidential) debate did was clarify the choice between the two visions of the parties and that helped us," said Rob Jesmer of the National Republican Senatorial Committee, which spearheads the GOP election effort.

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Jesmer said that of the 10 to 12 races that are polling within the margin of error, Republicans believe they are actually ahead by a couple of points in most of them. The Republican senatorial committee and GOP super PACS plan to spend heavily in Indiana, Wisconsin, North Dakota, Montana, Nevada, Arizona, and Virginia between now and the election.

"The races are close and millions of dollars will be spent" in the coming days, Jesmer said. "So we have to run to the tape."

Two years ago, Republicans were upbeat about their prospects because they only needed four seats to win the chamber outright and just three if a Republican were to win the White House and a GOP vice president could break tie votes.

Republicans had the advantage of having to protect only 10 seats while Democrats had to defend 23, many in narrowly divided swing states. In addition, several veteran Democratic incumbents, mostly moderates, announced they would retire, making it potentially even easier for Republicans to win those seats.

Republicans encountered their own problems, though.

A frustrated Sen. Olympia Snowe of Maine, who was considered a shoo-in for re-election, shocked her colleagues when she suddenly announced that she would leave the Senate, which she described as hopelessly partisan. In Missouri, the campaign of Rep. Todd Akin nearly collapsed after the Republican's comments about "legitimate rape" and his suggestion that women could biologically prevent pregnancy if they are raped. Until then, Republicans believed Akin would defeat Democratic Sen. Claire McCaskill, who polls showed was not very popular after just one term.

Now, Republicans are grappling with the controversy over Mourdock, the tea party-backed state treasurer. He had already riled the Republican establishment by defeating in the primary longtime moderate Sen. Richard Lugar, who otherwise likely would have won a seventh term. During a televised debate with his opponent, conservative Democratic Rep. Joe Donnelly, Mourdock defended his opposition to abortion even in the case of rape because, "I think even when life begins in that horrible situation of rape, that it is something God intended to happen."

Democrats pounced on his remarks and several key Republicans denounced them, too. Romney, who had just appeared in a TV ad for Mourdock, said he disagreed with the comment but didn't pull his endorsement.

Democrats, who this week pumped an additional $1.6 million into the race, say their internal polling shows Donnelly up by two points. However, Republicans say they are confident that the heavily GOP and pro-life voters in Indiana will rally behind Mourdock.

Strong Democratic candidates also have put several GOP seats into play.

In Arizona, former President George W. Bush's Surgeon General Richard Carmona, a Democrat who is Hispanic, is neck and neck with veteran GOP Rep. Jeff Flake. In Massachusetts, former Obama administration consumer advocate Elizabeth Warren appears to be slightly ahead of Sen. Scott Brown, the Republican who won the Senate seat that for decades belonged to Ted Kennedy. And in Nevada, many polls indicate Democratic Rep. Shelley Berkley narrowly trails Sen. Dean Heller, the Republican.

In three of the states where moderate Democratic incumbents retired this year and Republicans were early favorites to win, polls now show tight races. In Wisconsin, Democratic Rep. Tammy Baldwin is neck and neck with former GOP Gov. Tommy Thompson. In North Dakota, Democrat Heidi Heitkamp is slightly behind Republican Rep. Rick Berg and in New Mexico, Democratic Rep. Martin Heinrich is holding a small but steady lead of former Republican Rep. Heather Wilson.

But Republicans point to their own prospects, including seats they hope to pick up across the aisle.

At the top of their list is in Nebraska where Republican Deb Fischer has a solid lead over former Democratic Sen. Bob Kerrey and is likely to win the open Senate seat being vacated by Democrat Ben Nelson.

In Democratic-leaning Connecticut, Republican Linda McMahon, the former professional wrestling executive, hopes to win the seat of retiring Sen. Joe Lieberman, the independent who caucuses with Democrats. Her opponent is Democratic Rep. Chris Murphy, who has struggled to maintain a lead over McMahon. The race has been notably caustic with negative advertising flooding the airwaves. Democrats have had to spend heavily to shore up Murphy's campaign.

Polls are also very close in Montana where incumbent Democrat Jon Tester is locked in a slugfest with Republican Rep. Denny Rehberg and in Virginia where former Democratic Gov. Tim Kaine is trying to hold onto a Democratic seat over former Republican Sen. George Allen.

Democratic seats in Florida and Ohio are also in play although currently the Republican challengers appear to be behind.

Sen. Bob Casey, the Democratic incumbent from Pennsylvania who has led comfortably for most of the race, is trying to stave off a late surge from his opponent, business executive Tom Smith.

Republicans point to heavy spending by Democrats in blue sates like Pennsylvania, Connecticut, and Maine as evidence they have a chance to win enough seats to win the majority. Democrats point to heavy spending by Republicans in red states like Indiana and Montana as evidence they can't.

Operatives from both parties agree that many of these races could be determined by which presidential candidate carries the state, particularly in key battleground states like Florida, Virginia, Pennsylvania, Wisconsin, and Nevada.

As a sign of the high stakes over control of the Senate, a report out this week by the Sunlight Foundation says that outside groups spent a whopping $190 million on Senate races as of October 23.

Key senate race snapshots

Compiled by Adam Levy and Robert Yoon, CNN Political Research

Arizona: Rep. Jeff Flake (R) vs. Richard Carmona (D)

Open seat -- Sen. Jon Kyl (R) is retiring

This race has turned more competitive than originally expected. Democratic nominee Dr. Richard Carmona, a Vietnam veteran and a former U.S. Surgeon General under President George W. Bush, has proven a formidable opponent to six-term Rep. Jeff Flake, whose tough August primary for the GOP nomination left him bruised as he began the general election.

Tightening polls caused both campaigns to go negative with Flake accusing Carmona of having anger issues over an incident in which a former HHS official accused him of banging on her door in the middle of the night and scaring her family (Carmona denies the incident ever occurred). Carmona accuses Flake of not supporting veterans as a congressman (Flake says Carmona is cherry-picking votes and not looking at his entire record).

Democrats think their candidate's strengths and the state's growing Hispanic population will lead to their party's first successful Senate election since 1988. But Republicans point to no significant changes in Hispanic voting records, Flake's endorsements from Sens. Kyl and John McCain, and the state's traditional GOP support as reasons for a Flake victory.

California: Sen. Dianne Feinstein (D) vs. Elizabeth Emken (R)

Democratic incumbent Dianne Feinstein should easily win a fourth full term this November. Her GOP opponent is Elizabeth Emken, a former vice president for government relations at Autism Speaks.

Connecticut: Rep. Chris Murphy (D) vs. Linda McMahon (R)

Open seat -- Sen. Joseph Lieberman (I) is retiring

After waging a competitive but ultimately unsuccessful bid for U.S. Senate in 2010, former wrestling executive Linda McMahon is making a strong comeback this year. Buoyed by the millions of her own money she invested in the campaign, McMahon's made an effort to soften her image with ads about her personal life and combat attacks from third-term Rep. Chris Murphy.

Despite McMahon's significant financial advantage, Murphy is polling even or ahead of his opponent. In a state where President Barack Obama won by more than 20 points in 2008, a tie in the polls going into Election Day could mean a Murphy win on the president's coattails.

This is a tough state for Republicans in federal office. The last Connecticut Republican to hold a U.S. Senate seat left office in 1989.

Delaware: Sen. Tom Carper (D) vs. Kevin Wade (R)

Democrat Tom Carper has a clear path to winning a third term in November. He faces Republican businessman Kevin Wade.

Florida: Sen. Bill Nelson (D) vs. Rep. Connie Mack IV (R)

Democratic Sen. Bill Nelson's bid for a third term hasn't generated the competitive buzz originally expected in one of the most important presidential battleground states. Nelson's lead over four-term Rep. Connie Mack IV held steady throughout most of the campaign, though recent polls show Mack closing the gap.

TV ads from the candidates and outside groups have driven the race heavily, with less campaigning than usually seen in a U.S. Senate race in the Sunshine State on both sides. There was just one hour-long debate. Mack's poll numbers have improved as Romney's numbers have gone up in the state.

Hawaii:Rep. Mazie Hirono (D) vs. Former Gov. Linda Lingle (R)

Open seat -- Sen. Daniel Akaka (D) is retiring

Republicans fielded their best possible candidate in former Gov. Linda Lingle, but their hopes of upsetting third-term Rep. Mazie Hirono in this heavily Democratic state are fading.

Lingle, a popular former governor and formidable fundraiser, beat Hirono in the 2002 gubernatorial race, but in a presidential year the state's Democratic tilt and presence of a native son president heading the other party's ticket may be too much to overcome. Regardless of who wins, the state will elect its first female U.S. senator. If Hirono wins, she'll become the first Asian-American woman to serve in the U.S. Senate.

Indiana: Richard Mourdock (R) vs. Rep. Joe Donnelly (D)

Open seat -- Sen. Richard Lugar (R) was defeated in the primary

When six-term Republican Sen. Richard Lugar lost a bitter primary race to state treasurer Richard Mourdock, Democrats gained an unexpected opportunity to take over the seat with three-term Rep. Joe Donnelly.

Though Indiana is a Republican-leaning state, the polls have been close and some longtime Lugar supporters still haven't rallied behind the GOP nominee. Democrats pounded Mourdock for his comment at a debate two weeks before Election Day that "even when life begins in that horrible situation of rape, it is something that God intended." Mourdock the next day clarified his comment and added, "Rape is a horrible thing, and for anyone to twist my words otherwise is absurd and sick."

The full impact of the flap remains to be seen. Donnelly, a relatively conservative Democrat who opposes abortion rights, was one of few red-state Democrats to survive the Republican onslaught of 2010. He has kept the race competitive, but even with the Mourdock comments, Donnelly faces a Republican-friendly electorate and won't get much help from the top of the ticket.

The unexpected retirement of three-term Sen. Olympia Snowe has set the stage for a three-way contest between Democratic state senator Cynthia Dill, Republican Secretary of State Charlie Summers and former Gov. Angus King, an independent.

King, who quickly rose to frontrunner status, has declined to state until after the election which party he would caucus with in the Senate, though he is widely assumed to align with Democrats. The former governor has endorsements from the Human Rights Campaign, environmental groups and New York Mayor Michael Bloomberg's new super PAC, which supports gay rights, gun restrictions, and education reform.

The national Democratic party has not actively supported Dill but instead has run ads hammering Summers. The national Republicans focused much of their ad fire on King, with the hope that he and Dill will split enough of the anti-Republican vote to ensure a Summers victory. King was at 50% in a poll in mid-September.

Maryland: Sen. Ben Cardin (D) vs. Daniel Bongino (R)

Democrat Ben Cardin should easily beat former Secret Service agent Daniel Bongino for a second term in the U.S. Senate.

Massachusetts: Sen. Scott Brown (R) vs. Elizabeth Warren (D)

Massachusetts is perhaps the one race that has lived up to all its hype and more. As Republican Sen. Scott Brown competes for a full term against Harvard Law School professor Elizabeth Warren, the race for the state's few remaining undecided voters has taken a sharp tone. Brown launched harsh attacks questioning Warren's claims of Native-American heritage while also highlighting his own bipartisanship in the Senate.

Warren continues to attack Brown for protecting millionaires and for vowing to repeal Obamacare while highlighting her advocacy for the middle class and women's issues. Democrats hope the president's popularity and expected wide margin of victory in Romney's home state will counter Brown's popularity to make Warren the first woman to represent Massachusetts in the U.S. Senate.

Michigan: Sen. Debbie Stabenow (D) vs. Former Rep. Peter Hoekstra (R)

Though Democratic Sen. Debbie Stabenow appeared vulnerable at the beginning of the year in her bid for a third term, her fundraising and poll numbers quickly rose while Republicans searched for a candidate.

Winning a four-way primary was former Rep. Pete Hoekstra, who lost a 2010 primary bid for governor. President Barack Obama's popularity, in part due to the auto bailout along with the declining unemployment rate (above the national average, but down about 2 points from January 2009) gives Democrats reason to breathe easier in the Wolverine State.

Minnesota: Sen. Amy Klobuchar (D) vs. Kurt Bills (R)

Democrat Amy Klobuchar is expected to sail to a second term in November. She faces Republican state representative Kurt Bills.

Mississippi: Sen. Roger Wicker (R) vs. Albert N. Gore, Jr. (D)

Republican Roger Wicker should easily win his bid for a full term. He was appointed in 2007 and won a special election in 2008 to finish out the remainder of Trent Lott's term. He faces Democrat Albert N. Gore Jr., who is not a former vice president -- he's an octogenarian retired minister and ex-Green Beret.

Missouri: Sen. Claire McCaskill (D) vs. Rep. Todd Akin (R)

Plagued by scandals and a conservative electorate, Democrat Claire McCaskill seemed likely to become a one-term senator. That was until her opponent, six-term Republican Rep. Todd Akin, said in a local news interview that women have biological ways to avoid pregnancy after a "legitimate rape."

With a second wind to her campaign, McCaskill pounced as her poll numbers rose and Akin's dropped. Akin refused to drop out of the race despite requests from the GOP establishment. Some conservatives, including Jim DeMint, Newt Gingrich and Rick Santorum, rallied behind him. Other Republicans kept their distance, though some have come back around out of strong desire to unseat McCaskill.

With a lead over Akin, McCaskill sought to solidify her candidacy for a second term by running ads with female Republican rape survivors planning to vote for her because of Akin's comments. Missouri is still a competitive state for any Democrat, but unless local Republicans come back to Akin in droves, McCaskill appears headed to win a second term.

Montana: Sen. Jon Tester (D) vs. Rep. Dennis Rehberg (R)

Democrat Jon Tester knew he'd have an uphill battle to a second term against six-term Rep. Denny Rehberg. Both are known quantities with high favorables in the state, though neither has been able to crack 50% in the polls. Both campaigns have gone negative in the fight over Social Security, and both say the other is distorting their views.

Like the Massachusetts race, there are few undecideds left, except here Republicans are hoping that works in their favor. Though the state has a history of voting for Democrats statewide along with a Republican for president, Barack Obama's disapproval ratings could drive the strong GOP turnout Rehberg needs to move up a chamber in Congress.

Nebraska: Former Sen. Bob Kerrey (D) vs. Deb Fischer (R)

Open seat -- Sen. Ben Nelson (D) is retiring

Republicans began eyeing two-term Democrat Ben Nelson's seat even before he announced his retirement. With Nelson out, Democrats pinned their hopes on Bob Kerrey, the former governor and two-term senator. Although a well-known figure in Nebraska, Kerrey spent most of his post-Senate career outside of the state, primarily in New York City where he served as president of The New School.

The conservative super PAC American Crossroads began running ads against Kerrey before he even declared his candidacy. The Republican nominee is state Rep. Deb Fischer, who scored a surprising win in a crowded GOP primary. Kerrey has an uphill battle to keep the seat blue; Fischer has been leading with at least 50% in both independent and partisan polls.

Nevada: Sen. Dean Heller (R) vs. Rep. Shelley Berkley (D)

Democrats' strength in Nevada is being put to the test once again in a Senate election. With voter registration numbers on their side, seven-term Democratic Rep. Shelley Berkley hopes to deny Republican Sen. Dean Heller a full Senate term (Heller was appointed to the seat after Republican John Ensign resigned).

A House ethics investigation and a lackluster debate performance have kept Berkley below Heller in the most recent polls. Heller's strong fundraising ability also helped him keep the advantage in a state with a heavy Latino population that overwhelmingly votes Democratic. Both parties are hoping for a win here, though the race should remain close through Election Day. Turnout for the presidential race could have the largest impact on the outcome of this race.

New Jersey: Sen. Robert Menendez (D) vs. Joe Kyrillos (R)

Democrat Bob Menendez is expected to win a second term easily. He faces Republican state Sen. Joe Kyrillos.

Republicans were initially hopeful that Democratic incumbent Jeff Bingaman's decision to retire presented a pickup opportunity. Their nominee, former Rep. Heather Wilson, has a reputation for being a moderate in this increasingly Democratic-leaning state, but she lost a bruising Senate primary four years ago and has had difficulty getting her footing against Democratic nominee Martin Heinrich, a two-term congressman.

The two have been evenly matched in both fundraising and candidate-sponsored TV ads. However, according to ad spending data from the Campaign Media Analysis Group, the Democratic party and outside groups began pulling their ads in this race three months ago and most Republican groups have since followed suit, a sign that race was becoming less competitive. Both independent and partisan polling since the summer has shown Wilson stuck in the low 40s, with Heinrich leading by various margins.

Wilson also cannot rely on a competitive presidential race at the top of the ticket to help boost turnout in her favor. Heinrich enters the final stretch with a clear advantage.

New York: Sen. Kirsten Gillibrand (D) vs. Wendy Long (R)

Democrat Kirsten Gillibrand should easily win her first full term to the Senate. She faces attorney Wendy Long, a former clerk to Supreme Court Justice Clarence Thomas.

North Dakota: Heidi Heitkamp (D) vs. Rep. Rick Berg (R)

Open seat -- Sen. Kent Conrad (D) is retiring

Former state Attorney General Heidi Heitkamp gives Democrats their best opportunity to keep the seat of retiring five-term Sen. Kent Conrad. Republicans hope first-term Rep. Rick Berg will repeat the party's success of 2010, when they took over retiring Democrat Byron Dorgan's seat.

The state has a history of split-ticket voting, giving Heitkamp an opportunity to show her independence from national Democrats. She's publicly disagreed with Barack Obama on issues like energy, which she points to as evidence she won't be a rubber stamp. She enjoys high favorables and solid support from Republican ticket-splitters and has hammered Berg for his connection to a controversial real estate company.

With the lowest unemployment rate in the country, North Dakotans have their choice between two candidates with strong statewide appeal. This race will remain close until Election Day.

Ohio: Sen. Sherrod Brown (D) vs. Josh Mandel (R)

Amid the backdrop of what is arguably the nation's most competitive presidential battleground contest, first-term Senate incumbent Sherrod Brown hopes to prove that the Democratic wave that helped carry him into office in 2006 wasn't a fluke. Brown, who has a voting record the National Journal classified as one of the most liberal in the Senate, made a ripe target for Republicans looking for a pickup opportunity.

But in the home stretch of the 2012 campaign, Ohio remains conspicuously off the list of the most vulnerable Democratic-held seats. The Republican nominee is Josh Mandel, the 35-year-old state treasurer and Marine Corps veteran. Mandel has kept pace with Brown in terms of fundraising, but he continues to trail the incumbent by around 10 points in several independent polls from September and October.

Brown is far from having the race sewn up, especially with the daily volatility at the top of the ticket, but he has a leg up as the race enters its final days.

Pennsylvania: Sen. Bob Casey (D) vs. Tom Smith (R)

Recent polls have given Republicans hope where they previously had little. As Democratic Sen. Bob Casey's lead over Republican businessman Tom Smith began to tighten, the incumbent began actively campaigning across the state -- something he previously hadn't been doing.

Though Republicans have an opening now, Casey still enters the final stretch with the advantage. The state has not emerged as a contested presidential battleground and a strong showing by Barack Obama here could help Casey beat back this unexpected and late-breaking challenge.

Rhode Island: Sen. Sheldon Whitehouse (D) vs. Barry Hinckley (R)

Democrat Sheldon Whitehouse is a safe bet to win a second term in November. He faces Republican businessman Barry Hinckley.

Tennessee: Sen. Bob Corker (R) vs. Mark Clayton (D)

Unlike the tough battle he had in 2006 to take the seat, Republican Bob Corker should easily win a second term in November. He faces Democrat Mark Clayton, whose candidacy has been disavowed by the Tennessee Democratic Party for his involvement with an anti-gay rights group.

Texas: Ted Cruz (R) vs. Paul Sadler (D)

Open seat -- Sen. Kay Bailey Hutchison (R) is retiring

After a tough primary victory over the candidate endorsed by Gov. Rick Perry and the state party establishment, Republican nominee Ted Cruz, the former state solicitor general, is now heavily favored this November in his race against Democratic nominee Paul Sadler, a former state representative.

Utah: Sen. Orrin Hatch (R) vs. Scott Howell (D)

Republican Orrin Hatch learned an important lesson from his former colleague Sen. Bob Bennett in 2010 -- don't take the Republican nomination for granted. Hatch campaigned early and hard to win the GOP nomination over tea party favorite Dan Liljenquist, a former state senator. Hatch now is the overwhelming favorite to win a seventh term in November.

A Democrat hasn't represented Utah in the U.S. Senate in 36 years.

Vermont: Sen. Bernie Sanders (I) vs. John MacGovern (R)

Independent Bernie Sanders, the Senate's only self-described socialist, is expected to sail to a second term over Republican John MacGovern, a former Massachusetts state representative and unsuccessful congressional candidate.

Republican George Allen is fighting hard to win back the seat he lost six years ago to now-retiring Democratic Sen. Jim Webb. A strong Democratic wave, along with a gaffe caught on tape that became infamous on YouTube, stripped Allen of what was expected to be his second term (and perhaps a launching pad to the 2008 GOP presidential nomination). He now faces Democratic nominee Tim Kaine, another former governor, in one of the marquee Senate races of 2012.

Polls remain close. Barack Obama's win in Virginia in 2008 and the strong play he's making for the state in 2012 have given Kaine organizational support. Allen has run ads linking Kaine, the chairman of the Democratic National Committee at the start of the Obama administration, to the president and to looming budget cuts. Kaine, in turn, has run ads tying Allen to George W. Bush's economic policies and that he's wrong on women's issues.

Both candidates have seen their leads grow and shrink with the presidential candidates. It's very likely the winner of the Senate seat will be a member of the same party of the presidential candidate who wins Virginia's 13 electoral votes.

Washington: Sen. Maria Cantwell (D) vs. Michael Baumgartner (R)

Democrat Maria Cantwell is expected to win a third term in November. She faces Republican state Sen. Michael Baumgartner.

West Virginia: Sen. Joe Manchin (D) vs. John Raese (R)

No, we did not forget to update this section from 2010. Democrat Joe Manchin once again faces Republican businessman John Raese in the contest to win his first full term. Manchin has proven his independence from the president and faces a much easier race this time to win in November.

Wisconsin: Rep. Tammy Baldwin (D) vs. former Gov. Tommy Thompson (R)

Open seat -- Sen. Herb Kohl (D) is retiring

Former Gov. Tommy Thompson won a tough Republican primary to take on seven-term Democratic Rep. Tammy Baldwin for retiring incumbent Herb Kohl's Senate seat. Thompson's attacks on Baldwin as being too liberal haven't had the impact he was hoping. The polls are very close, but Baldwin has pulled slightly ahead recently, though not outside the margin of error.

Unless vice presidential candidate and native son Paul Ryan brings out strong turnout for the party, the state's historic Democratic tilt in presidential elections could help Baldwin succeed to becoming the first openly gay senator.

Wyoming: Sen. John Barrasso (R) vs. Tim Chesnut (D)

Republican John Barrasso is expected to win a second term in November. He faces Democratic nominee Tim Chesnut, an Albany County commissioner.